Pfizer Inc. is seeking a six-week to eight-week delay in litigation over alleged birth defects from the use of antidepressant Zoloft. If the judge agrees, the first trials would begin in January.

The schedule in the multidistrict litigation has been aggressive but “there remains a critical disparity” in the progress of discovery in cases selected for trial by the plaintiffs as opposed to those chosen by Pfizer, because the plaintiffs have dismissed 14 of the drugmaker’s picks, the company said.